One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,13,20,15,21,14,19)(11,22,24,16,26,33,25,17)(12,27,29,18,31,36,30,37)(23,34,28,38,40,32,39,35)(1,3)(2,5)(4,7)(6,8)(9,11,13,24,15,26,14,25)(10,16,19,22,21,17,20,33)(12,23,29,28,31,40,30,39)(18,32,27,38,37,34,36,35)(3,7)(5,8)(9,11,15,26)(10,17,21,16)(12,28,31,39)(13,25,14,24)(18,35,37,38)(19,22,20,33)(23,30,40,29)(27,34,36,32)(9,12,13,29,15,31,14,30)(10,18,20,36,21,37,19,27)(11,23,24,28,26,40,25,39)(16,32,33,35,17,34,22,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.